Image display device and drive device therefor

ABSTRACT

An image display device including a field emission element capable of preventing diffusion of electrons to be impinged on a display section. An anode substrate is provided thereon with a phosphor-deposited display section and a cathode substrate is provided thereon with field emission elements including cathode conductors, emitter electrodes and gate electrodes. The cathode conductors and gate electrodes are formed into a stripe-like shape and arranged so as to intersect each other to form a matrix. A stripe-like diffusion prevention electrode is arranged between each adjacent two of the gate electrodes. The emitter electrodes selected by the gate electrodes and cathode conductors emit electrons. The diffusion prevention electrodes on both sides of each of the gate electrodes selected are applied thereto a voltage lower than a voltage of the gate electrodes, so that the electrons may be impinged on the display section required without diffusion, to thereby permit picture cells required to emit light.

This is a Division of application Ser. No. 08/777,193 filed on Dec. 27,1996, now U.S. Pat. No. 5,703,611, which is a continuation of Ser. No.08/251,245, filed May 31, 1994, now abandoned.

BACKGROUND OF THE INVENTION

This invention relates to an electron emission element of the fieldemission type suitable for use for a microwave vacuum tube, a lightsource, an amplification element, a high-speed switching element, asensor or the like and an image display device using such an electronemission element as a cathode, and more particularly to an electronemission element conveniently applicable to a color display device inwhich a field emission cathode is incorporated.

Application of an electric field of about 10⁹ V/m to a metal surface ora semiconductor surface causes electrons to pass through a barrier by atunnel effect, resulting in the electrons being discharged into a vacuumatmosphere even at a normal temperature. Such a phenomenon is calledfield emission and a cathode constructed so as to emit electrons basedon such a principle is called a field emission cathode (hereinafter alsoreferred to as "FEC").

Recent progress in techniques for processing a semiconductor has led todevelopment of an FEC of the surface-emission type including FEC arraysof a micron size.

Now, a conventional image display device will be described by way ofexample with reference to FIG. 28.

The conventional image display device includes an anode substrate 400and a cathode substrate 401 arranged oppositely to each other and sideplates (not shown) arranged so as to surround an outer periphery of eachof the substrates 400 and 401, resulting in an envelope 402 beingprovided, which is then evacuated to a high vacuum. The anode substrate400 is provided on an inner surface thereof with a display section 405comprising a light-permeable anode conductor 403 and phosphor layers 404deposited thereon.

The cathode substrate 401 is provided on an inner surface thereofopposite to the display section 405 of the anode substrate 400 withfield emission elements each including emitter electrodes 406 of aconical shape. More particularly, the cathode substrate 401 is providedon the inner surface thereof with stripe-like cathode conductors 407,each of which is provided thereon with an insulating layer 409 formedwith openings 408. The apertures 408 each are provided therein with anemitter electrode 406 acting as a conical electron emitter while beingarranged on the cathode conductor 407. The insulating layer 409 isprovided on an upper surface thereof with stripe-like gate electrodes411 each formed with apertures 410 in a manner to be aligned with theopenings 408 and arranged so as to extend in a direction across thecathode conductors 407.

Thus, the cathode conductors 407 and gate electrodes 411 cooperate witheach other to form a matrix, so that when application of an anodevoltage of a predetermined level to the display section 405 and drivingof each of the cathode conductors 407 and gate electrodes 411 at asuitable timing permit the emitter electrodes 406 from which electronsare to be emitted to be selected, resulting in the phosphor layers 404of the display section 405 opposite to the selected emitter electrodes406 being selectively driven, leading to a desired luminous display.

In the conventional image display device, the emitter electrodes 406each are formed into a conical shape and the gate electrodes 411 eachare arranged so as to surround a tip end of each of the emitterelectrodes 406, so that electrons emitted from the emitter electrodes406 are caused to be spread at an angle of, for example, about 30degrees on each of sides although it is of course that the spreading issomewhat varied depending on a voltage applied to the anode conductor403 of the display section 405. Thus, when it is desired to obtain adisplay with high definition and fine picture cell pitches, it isrequired to decrease an interval between the field emission typecathodes and the display section or reduce a region in which the fieldemission type cathodes are arranged with respect to pitches ofarrangement of picture cells. Otherwise, electrons diffused as describedabove are caused to impinge on adjacent picture cells, leading toleakage luminescence of the adjacent picture cells.

Unfortunately, in order to increase luminance of picture cells, it isrequired to increase an anode voltage of the display section. However,this requires to somewhat increase a distance between the display deviceand the cathodes, to thereby ensure insulation therebetween. Forexample, supposing that an anode voltage of 1 kV is applied to thedisplay section 405, it is required that the interval between thephosphor layers 404 and the gate electrodes 411 is set to be 150 to 200um.

Such an electron emission element of the field emission type asdescribed above is widely used in the field of a microwave vacuum tube,a light source, an amplification element, a high-speed switchingelement, a sensor or the like.

Now, a display with high definition which is obtained at picture cellpitches as small as, for example, 0.33 mm or less in a display device ofwhich a display is selected by means of gate electrodes and emitterelectrodes will be discussed hereinafter. When it is desired to obtainsuch a display in the form of, for example, a full color display, it isrequired to construct a color display device in such a manner thatpicture cells which are constituted by phosphor layers R, G and B areformed into a width of about 80 um and arranged at intervals of about 20um.

Supposing that a distance between the phosphor layers 404 and the gateelectrodes 411 is set to be 150 um and an angle of spreading ofelectrons emitted by the conical emitter electrodes 406 is 30 degrees oneach side, the electrons are caused to spread by a distance of about 80um on each side. This leads to a failure in proper operation of adisplay device including picture cells having such dimensions asdescribed above, to thereby fail to provide the display with such highdefinition as described above. On the contrary, a decrease in distancebetween the phosphor layers 404 and the gate electrodes 411 to about 50um permits spreading of the electrons to be minimized. However, thisrenders an increase in anode voltage impossible in view of dielectricstrength, leading to a decrease in luminance.

Also, when spreading of electrons emitted occurs in a microwave vacuumtube, a light source, an amplification element, a high-speed switchingelement, a sensor or the like in which the above-described fieldemission element is incorporated, the amount of electrons reaching ananode (collector) is reduced, leading to a deterioration in S/N ratiowith respect to input power or a failure to increase sensitivity, tothereby render light emission unstable.

A field emission cathode (FEC) is generally formed into a planarconfiguration, so that a field emission cathode of the surface emissiontype may be provided. Thus, application of such a field emission cathodeof the surface emission type to a color display device has beenproposed. Such a conventional color display device may be generallyconstructed in such a manner as shown in FIG. 23.

More particularly, a second substrate 105 arranged opposite to a firstsubstrate 101 is provided thereon with a plurality of anode electrodegroups each including three stripe-like anode electrode elements 106-1,106-2 and 106-3 which are provided thereon with a phosphor (R) of a redluminous color, a phosphor (G) of a green luminous color and a phosphor(B) of a blue luminous color, respectively. The stripe-like anodeelectrode elements 106-1, 106-2 and 106-3 for the phosphors of therespective luminous colors are commonly connected to anode lead-outelectrodes A1, A2 and A3, respectively, which are then led out of thesecond substrate 105.

The first substrate 101 is formed thereon with cathode electrodes 102,each of which is formed thereon with emitter arrays 104 including aplurality of conical emitters for field-emitting electrons. Each of thecathode electrodes 102 is formed thereon with gate electrodes 103 whilekeeping the gate electrodes 103 insulated from the cathode electrode102.

Thus, the anode electrode elements 106-1 cooperate with each other toform an anode electrode for emitting only light of a red luminous color,the anode electrode elements 106-2 form an anode electrode for emittingonly light of a green luminous color and the anode electrode elements106-3 form an anode electrode for emitting only light of a blur luminouscolor.

Arrangement of the above-described electrodes is shown in FIG. 22, whichis viewed from a side of the anode electrodes. As shown in FIG. 22, theanode lead-out electrodes A1, A2 and A3 are led out of the anodeelectrode elements 106-1, 106-2 and 106-3 on both sides of thesubstrate, respectively. The gate electrodes 103 (103-1, 103-2, . . . ,103-1) are formed in a manner to be spaced from and parallel to theanode electrode elements 106-1 to 106-3. The gate electrodes 103 eachare provided with gate lead-out electrodes GT1, GT2, . . . , GTl in amanner to be led out thereof, respectively.

In order that the emitter arrays 104 (104-1, 104-2, . . . ) from whichemission of electrons is controlled by the gate electrodes 103-1, 103-2,. . . , 103-1 cause each one set of picture cells R, G and B to emitlight, the gate electrodes 103-1, 103-2, 103-1 are formed so as tostraddle the anode electrode elements 106-1 to 106-3 corresponding toeach one set of picture cells R, G and B.

The cathode electrodes 102 are formed into a stripe-like shape andarranged below the gate electrodes 103-1, 103-2, . . . , 103-1 so as toextend in a direction perpendicular to the anode electrodes 106-1 to106-3. Also, the cathode electrodes 102 are provided with cathodelead-out electrode C1, C2, . . . , Cn in a manner to be led out thereof,respectively. The emitter arrays 104 are arranged on each of the cathodeelectrodes 102. The anode electrode elements 106-1 each have thephosphor R of a red luminous color deposited thereon, the anodeelectrode elements 106-2 each have the phosphor G of a green luminouscolor deposited thereon, and the anode electrode elements 106-3 eachhave the phosphor B of a blue luminous color deposited thereon.

In order to cause the color display device constructed as describedabove to display a color image, a contact al to which the lead-outelectrode A1 of each of the anode electrode elements 106-1 is connectedis selected through changing-over of a switch 100 to cause an anodevoltage Ea to be applied to the anode electrode elements 106-1.Concurrently, selection of the cathode electrodes 102 is carried out byclosing a switch 110 and color data on a red luminous color are fed tothe gate lead-out electrodes GT1, GT2, . . . , GTl to cause the displaydevice to display an image of a red luminous color on one line. Then,the cathode lead-out electrodes C1 to Cn are scanned in turn to causethe display device to display an image of a red luminous color.

Subsequently, the switch 100 is changed over to a position of a contacta2 to which the anode lead-out electrode A2 is connected, to therebycause the anode voltage Ea to be applied to the anode electrode elements106-2. Concurrently, the cathode lead-out electrodes C1 to Cn arescanned in turn and data on a green luminous color are fed to the gateelectrodes GT1 to GTl in synchronism with the scanning, resulting in thedisplay device displaying an image of a green luminous color.

Thereafter, the switch 100 is changed over to a position of a contact a3to which the anode lead-out electrode A3 is connected to cause the anodevoltage Ea to be applied to the anode electrode elements 106-3.Concurrently, the cathode lead-out electrodes C1 to Cn are scanned inturn and data on a blue luminous color are fed to the gate electrodesGT1 to GTl in synchronism with the canning, to thereby cause the displaydevice to display an image of a blue luminous color. Thus, theconventional color display device displays a color image according to asurface sequential system.

In the conventional color display device in which the anode electrodeseach are constituted by the three anode electrode elements, it isrequired to lead out each three anode lead-out electrodes A1, A2 and A3from the second substrate 105 because the anode electrode elements106-1, 106-2 and 106-3 are formed on the second substrate 105.Unfortunately, leading-out of each three anode lead-out electrodes A1,A2 and A3 from the second substrate causes multi-level crossing of theelectrodes as indicated at reference characters a, b and c in FIG. 22,so that it is required to arrange the electrodes in a three-dimensionalwiring manner.

Also, each of the anode electrodes is formed of three anode electrodeelements, therefore, a duty determined by the number of times ofscanning of the cathode lead-out electrodes C1 to Cn is reduced to alevel of 1/3, resulting in an image plane of the display device beingdecreased in brightness.

In order to solve the above-described problems, it would be consideredthat a construction of the color display device in such a manner thatonly one anode lead-out electrode is arranged and the cathode lead-outelectrodes and gate lead-out electrodes are scanned to selectively drivethe phosphors R, G and B arranged on the anode electrode elementspermits the display device to display a color image while eliminatingthe above-described three-dimensional arrangement or wiring of the anodelead-out electrodes. However, such a construction of the display devicefails to prevent bleeding of an image due to leakage luminescence ofadjacent phosphors because electrons emitted from the cathode electrodesreach the anode electrodes while spreading to a degree, as will beunderstood from the widely-known fact that electrons emitted fromcathode electrodes generally travel to anodes while spreading at anangle of about 30 degrees.

Also, in the conventional image display device in which the fieldemission cathodes are incorporated, a voltage applied to the anodeelectrodes is within a range between hundreds volts and thousands bolts,to thereby fail to meet all luminous characteristics of the phosphorssuch as luminous efficiency, color purity, durability and the like.Thus, when it is desired to directly observe luminescence from thephosphors, the image display device fails to permit the phosphors toexhibit desired luminance. In particular, the conventional image displaydevice causes the phosphor of a red luminous color to be deteriorated inluminous characteristics or efficiency as compared with the phosphors ofother luminous colors.

Further, the conventional image display device uses a filter in order toincrease color purity of a display and contrast thereof to obtain aplurality of luminous colors from the same phosphor. Unfortunately useof the filter substantially fails to permit the phosphors to exhibitdesired luminescence and luminance and causes non-uniformity inluminescence and luminance between the phosphors.

SUMMARY OF THE INVENTION

The present invention has been made in view of the foregoingdisadvantages of the prior art.

Accordingly, it is an object of the present invention to provide animage display device which is capable of permitting anode lead-outelectrodes for anode electrodes to be led out of the anode electrodeswithout multi-level crossing of the anode lead-out electrodes.

It is another object of the present invention to provide an imagedisplay device which is capable of providing a color image free of anybleeding of luminous color.

It is a further object of the present invention to provide an imagedisplay device which is capable of significantly increasing duty inimage displaying to provide balanced luminescence and luminanceirrespective of a luminous color of a phosphor.

It is still another object of the present invention to provide a drivecircuit for an image display device which is capable of permitting anodelead-out electrodes for anode electrodes to be led out of the anodeelectrodes without multi-level crossing of the anode lead-outelectrodes.

It is yet another object of the present invention a drive circuit for animage display device which is capable of permitting the image displaydevice to provide a color image free of any bleeding of luminous color.

It is even another object of the present invention to provide a drivecircuit for an image display device which is capable of permitting theimage display device to significantly increase duty in image displayingto provide balanced luminescence and luminance irrespective of aluminous color of a phosphor.

In accordance with one aspect of the present invention, an image displaydevice is provided. The image display device includes an airtightenvelope including an anode substrate and a cathode substrate arrangedso as to be opposite to each other, cathodes electron emitting elementsof the field emission type which include cathode conductors arranged onan inner surface of the cathode substrate, emitter electrodes providedon each of the cathode conductors and gate electrodes arranged on eachof the cathode conductors through an insulating layer, and a displaysection formed on an inner surface of the anode substrate. The gateelectrodes each have a selection voltage applied thereto to causeelectrons emitted from the emitter electrodes to impinge on the displaysection, resulting in the display section carrying out a luminousdisplay. The device also includes diffusion prevention electrodesarranged on the same plane as the gate electrodes in a manner tointerpose each of the gate electrodes between each adjacent two of thediffusion prevention electrodes and applied thereto a voltage lower thanthe selection voltage when the selection voltage is applied to at leastthe gate electrodes positioned in proximity to the diffusion preventionelectrodes, to thereby prevent diffusion of electrons emitted from theemitter electrodes.

In accordance with this aspect of the present invention, an imagedisplay device is provided. The image display device includes a firstsubstrate, a plurality of stripe-like cathode electrodes formed on thefirst substrate and including emitters for field-emitting electrons,cathode lead-out electrodes led out of the cathode electrodes,respectively, a plurality of stripe-like gate electrodes arranged on thecathode electrodes in a manner to be perpendicular to the cathodeelectrodes while being kept insulated from the cathode electrodes, gatelead-out electrodes led out of the gate electrodes, a second substratearranged in a manner to be spaced by a predetermined distance from thefirst substrate, stripe-like anode electrodes formed on the secondsubstrate in a manner to be opposite to the gate electrodes andperpendicular to the cathode electrodes, two anode lead-out electrodesalternately connected to the stripe-like anode electrodes and led out ofthe anode electrodes on both sides of the second substrate,respectively, and phosphors arranged on the stripe-like anode electrodesin turn, to thereby provide red, blue and green luminous colors.

In a preferred embodiment, the red, blue and green luminous colors maybe obtained through a filter means.

In a preferred embodiment of the present invention, each one of thestripe-like gate electrodes is positioned below each adjacent two of thestripe-like anode electrodes, so that each one gate electrode controlsluminescence of the phosphors arranged on each two anode electrodes.

Also, in accordance with this aspect of the present invention, an imagedisplay device is provided. The image display device includes a firstsubstrate, a plurality of stripe-like cathode electrodes formed on thefirst substrate and including emitters for field-emitting electrons,cathode lead-out electrodes led out of the cathode electrodes,respectively, a plurality of stripe-like gate electrodes arranged on thecathode electrodes in a manner to be perpendicular to the cathodeelectrodes while being kept insulated from the cathode electrodes, gatelead-out electrodes led out of the gate electrodes, respectively, asecond substrate arranged in a manner to be spaced by a predetermineddistance from the first substrate, stripe-like anode electrodes formedon the second substrate in a manner to be opposite to the gateelectrodes and perpendicular to the cathode electrodes and providedthereon with phosphors of red, blue and green luminous colors in turn, afirst anode lead-out electrode to which the first anode electrode havingthe phosphor of the worst luminous efficiency provided thereon isconnected, and a second anode lead-out electrode to which the secondanode electrodes having the remaining phosphors formed thereon areconnected. The stripe-like gate electrodes are so arranged that two suchgate electrodes are positioned below the first anode electrodes and onesuch gate electrode is positioned below the second anode electrodes.

Further, in accordance with this aspect of the present invention, animage display device is provided. The image display device includes afirst substrate, a plurality of stripe-like cathode electrodes formed onthe first substrate and including emitters for field-emitting electrons,cathode lead-out electrodes led out of the cathode electrodes,respectively, a plurality of stripe-like gate electrodes arranged on thecathode electrodes in a manner to be perpendicular to the cathodeelectrodes while being kept insulated from the cathode electrodes, gatelead-out electrodes led out of the gate electrodes, respectively, asecond substrate arranged in a manner to be spaced by a predetermineddistance from the first substrate, and stripe-like anode electrodesformed on the second substrate in a manner to be opposite to the gateelectrodes and perpendicular to the cathode electrodes. The stripe-likeanode electrodes are provided thereon with phosphors, respectively. Thedevice also includes a filter means arranged for permitting lightsemitted from the phosphors to pass therethrough, to thereby obtain red,blue and green luminous colors from the anode electrodes in turn, afirst anode lead-out electrode to which the first anode electrode havingthe phosphor of the worst luminous efficiency provided thereon isconnected, and a second anode lead-out electrode to which the secondanode electrodes having the remaining phosphors formed thereon areconnected. The stripe-like gate electrodes are so arranged that two suchgate electrodes are positioned below the first anode electrodes and onesuch gate electrode is positioned below the second anode electrodes.

In a preferred embodiment of the present invention, the image displaydevice further includes a control electrode arranged between eachadjacent two of the gate electrodes for controlling spreading ofelectrons emitted from the emitters.

In accordance with another aspect of the present invention, a drivedevice for an image display device is provided. The drive deviceincludes a first substrate, a plurality of stripe-like cathodeelectrodes formed on the first substrate and including emitters forfield-emitting electrons, cathode lead-out electrodes led out of thecathode electrodes, respectively, a plurality of stripe-like gateelectrodes arranged on the cathode electrodes in a manner to beperpendicular to the cathode electrodes while being kept insulated fromthe cathode electrodes, gate lead-out electrodes led out of the gateelectrodes, a second substrate arranged in a manner to be spaced by apredetermined distance from the first substrate, stripe-like anodeelectrodes formed on the second substrate in a manner to be opposite tothe gate electrodes and perpendicular to the cathode electrodes, twoanode lead-out electrodes alternately connected to the stripe-like anodeelectrodes and led out of the anode electrodes on both sides of thesecond substrate, respectively, phosphors respectively arranged on thestripe-like anode electrodes, to thereby provide red, blue and greenluminous colors in turn, and a scanning means for scanning the cathodelead-out electrodes in turn while one of the anode lead-out electrodesis kept selected and then scanning the cathode lead-out electrodes inturn while the other of the anode lead-out electrodes is kept selected.The scanning means permits the image display device to display an image.

In a preferred embodiment of the present invention, color datacorresponding to scanning of the cathode lead-out electrodes are fed tothe gate lead-out electrodes in synchronism with the scanning of thecathode lead-out electrodes.

In accordance with this aspect of the present invention, a drive devicefor an image display device is provided. The drive device includes afirst substrate, a plurality of stripe-like cathode electrodes formed onthe first substrate and including emitters for field-emitting electrons,cathode lead-out electrodes led out of the cathode electrodes,respectively, a plurality of stripe-like gate electrodes arranged on thecathode electrodes in a manner to be perpendicular to the cathodeelectrodes while being kept insulated from the cathode electrodes, gatelead-out electrodes led out of the gate electrodes, a second substratearranged so as to be spaced by a predetermined distance from the firstsubstrate, stripe-like anode electrodes formed on the second substratein a manner to be opposite to the gate electrodes and perpendicular tothe cathode electrodes, two anode lead-out electrodes alternatelyconnected to the stripe-like anode electrodes and led out of the anodeelectrodes on both sides of the second substrate, respectively,phosphors respectively arranged on the stripe-like anode electrodes, tothereby provide red, blue and green luminous colors in turn, a firstscanning means for scanning the cathode lead-out electrodes in turn, anda second scanning means for scanning the anode lead-out electrodes whileone of the cathode lead-out electrodes is kept selectively scanned. Thefirst and second scanning means permit the image display device todisplay an image.

In accordance with a further aspect of the present invention, there isprovided an image display drive device for an image display device whichincludes a first substrate, a plurality of stripe-like cathodeelectrodes formed on the first substrate and including emitters forfield-emitting electrons, cathode lead-out electrodes led out of thecathode electrodes, respectively, a plurality of stripe-like gateelectrodes arranged on the cathode electrodes in a manner to beperpendicular to the cathode electrodes while being kept insulated fromthe cathode electrodes, gate lead-out electrodes led out of the gateelectrodes, respectively, a second substrate arranged in a manner to bespaced by a predetermined distance from the first substrate, stripe-likeanode electrodes formed on the second substrate in a manner to beopposite to the gate electrodes and perpendicular to the cathodeelectrodes and provided thereon with phosphors of red, blue and greenluminous colors in turn, a first anode lead-out electrode to which thefirst anode electrode having the phosphor of the worst luminousefficiency provided thereon is connected, and a second anode lead-outelectrode to which the second anode electrodes having the remainingphosphors formed thereon are connected. The stripe-like gate electrodesare so arranged that two such gate electrodes are positioned below thefirst anode electrodes and one such gate electrode is positioned belowthe second anode electrodes. The image display drive device is featuredin that the cathode lead-out electrodes are fully scanned in turn whileone of the anode lead-out electrodes is kept selected and then thecathode lead-out electrodes are fully scanned while the other of theanode lead-out electrodes is kept selected, resulting in an image forone frame being displayed on the image display device.

Also, in accordance with this aspect of the present invention, there isprovided an image display drive device for an image display device whichincludes a first substrate, a plurality of stripe-like cathodeelectrodes formed on the first substrate and including emitters forfield-emitting electrons, cathode lead-out electrodes led out of thecathode electrodes, respectively, a plurality of stripe-like gateelectrodes arranged on the cathode electrodes in a manner to beperpendicular to the cathode electrodes while being kept insulated fromthe cathode electrodes, gate lead-out electrodes led out of the gateelectrodes, respectively, a second substrate arranged in a manner to bespaced by a predetermined distance from the first substrate, stripe-likeanode electrodes formed on the second substrate in a manner to beopposite to the gate electrodes and perpendicular to the cathodeelectrodes and provided thereon with phosphors, respectively, a filtermeans arranged for permitting lights emitted from the phosphors to passtherethrough, to thereby provide red, blue and green luminous colorsfrom the anode electrodes in turn, a first anode lead-out electrode towhich the first anode electrode having the phosphor of the worstluminous efficiency provided thereon is connected, and a second anodelead-out electrode to which the second anode electrodes having theremaining phosphors formed thereon are connected. The stripe-like gateelectrodes are so arranged that two such gate electrodes are positionedbelow the first anode electrodes and one such gate electrode ispositioned below the second anode electrodes. The image display drivedevice is featured in that the cathode lead-out electrodes are fullyscanned in turn while one of the anode lead-out electrodes is keptselected and then the cathode lead-out electrodes are fully scannedwhile the other of the anode lead-out electrodes is kept selected,resulting in an image for one frame being displayed on the image displaydevice.

Further, in accordance with this aspect of the present invention, thereis provided image display drive device for an image display device whichincludes a first substrate, a plurality of stripe-like cathodeelectrodes formed on the first substrate and including emitters forfield-emitting electrons, cathode lead-out electrodes led out of thecathode electrodes, respectively, a plurality of stripe-like gateelectrodes arranged on the cathode electrodes in a manner to beperpendicular to the cathode electrodes while being kept insulated fromthe cathode electrodes, gate lead-out electrodes led out of the gateelectrodes, respectively, a second substrate arranged in a manner to bespaced by a predetermined distance from the first substrate, stripe-likeanode electrodes formed on the second substrate in a manner to beopposite to the gate electrodes and perpendicular to the cathodeelectrodes and provided thereon with phosphors of red, blue and greenluminous colors in turn, a first anode lead-out electrode to which thefirst anode electrode having the phosphor of the worst luminousefficiency provided thereon is connected, and a second anode lead-outelectrode to which the second anode electrodes having the remainingphosphors formed thereon are connected. The stripe-like gate electrodesare so arranged that two such gate electrodes are positioned below thefirst anode electrodes and one such gate electrode is positioned belowthe second anode electrodes. The image display drive device is featuredin that the cathode lead-out electrodes are scanned in turn and thefirst and second anode electrodes are scanned while one of the cathodelead-out electrodes is kept selectively scanned, so that the cathodelead-out electrodes are fully scanned to cause an image for one frame tobe displayed on the image display device.

Furthermore, in accordance with this aspect of the present invention,there is provided an image display drive device for an image displaydevice which includes a first substrate, a plurality of stripe-likecathode electrodes formed on the first substrate and including emittersfor field-emitting electrons, cathode lead-out electrodes led out of thecathode electrodes, respectively, a plurality of stripe-like gateelectrodes arranged on the cathode electrodes in a manner to beperpendicular to the cathode electrodes while being kept insulated fromthe cathode electrodes, gate lead-out electrodes led out of the gateelectrodes, respectively, a second substrate arranged in a manner to bespaced by a predetermined distance from the first substrate, stripe-likeanode electrodes formed on the second substrate in a manner to beopposite to the gate electrodes and perpendicular to the cathodeelectrodes and provided thereon with phosphors, respectively, a filtermeans arranged for permitting lights emitted from the phosphors to passtherethrough, to thereby obtain red, blue and green luminous colors fromthe anode electrodes in turn, a first anode lead-out electrode to whichthe first anode electrode having the phosphor of the worst luminousefficiency provided thereon is connected, and a second anode lead-outelectrode to which the second anode electrodes having the remainingphosphors formed thereon are connected. The stripe-like gate electrodesare so arranged that two such gate electrodes are positioned below thefirst anode electrodes and one such gate electrode is positioned belowthe second anode electrodes. The image display drive circuit is featuredin that the cathode lead-out electrodes are scanned in turn and thefirst and second anode electrodes are scanned while one of the cathodelead-out electrodes is kept selectively scanned, so that the cathodelead-out electrodes are fully scanned to cause an image for one frame tobe displayed on the image display device.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects and many of the attendant advantages of thepresent invention will be readily appreciated as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings; wherein:

FIG. 1 is an exploded perspective view showing an embodiment of an imagedisplay device according to the present invention;

FIG. 2 is a sectional view showing a modification of the image displaydevice of FIG. 1;

FIG. 3 is a sectional view showing another modification of the imagedisplay device of FIG. 1;

FIG. 4 is a sectional view showing a further modification of the imagedisplay device of FIG. 1;

FIG. 5 is a graphical representation showing a current densitydistribution formed by electrons emitted from cathode electrodes;

FIG. 6 is a diagrammatic view showing an electric filed distributionbetween cathode electrodes and anode electrodes;

FIG. 7 is a schematic plan view showing arrangement of electrodes in theimage display device of FIG. 3;

FIG. 8 is a block diagram showing an embodiment of a drive device for animage display device according to the present invention;

FIGS. 9(a) to 9(k), 9(m), 9(n) and 9(p) each are a timing chart of thedrive device shown in FIG. 8;

FIGS. 10(a) to 10(d) each are a schematic view showing selection ofpicture cells by the drive device of FIG. 8;

FIG. 11 is a block diagram showing another embodiment of a drive devicefor an image display device according to the present invention;

FIGS. 12(a) to 12(k), 12(m), 12(n), and 12(p) each are a timing chart ofthe drive device shown in FIG. 11;

FIG. 13(a) to 13(d) each are a schematic view showing selection ofpicture cells by the drive device of FIG. 11;

FIGS. 14 and 15 each are a sectional view showing another embodiment ofan image display device according to the present invention;

FIGS. 16(a) and 16(b) each are a diagrammatic view showing an electricfield distribution;

FIG. 17 is a schematic plan view showing arrangement of electrodes inthe image display device of each of FIG. 14 and 15;

FIGS. 18(a) to 18(k), 18(m), 18(n), 18(p) and 18(q) each are a timingchart of a drive circuit for the image display device of each of FIGS.14 and 15;

FIGS. 19(a) to 19(d) each are a schematic view showing selection ofpicture cells by the drive device of each of FIGS. 14 and 15;

FIGS. 20(a) to 20(k), 20(m), 20(n) and 20(p) each are a timing chart ofanother drive circuit for the image display device of each of FIGS. 14and 15;

FIGS. 21(a) to 21(d) each are a schematic view showing another selectionof picture cells by the drive device of each of FIGS. 14 and 15;

FIG. 22 is a schematic plan view showing an anode electrodes in aconventional image display device;

FIG. 23 is sectional view showing a conventional image display device;

FIG. 24 is fragmentary sectional view showing another embodiment of animage display device according to the present invention;

FIG. 25 is a plan view showing a cathode substrate in the image displaydevice of FIG. 24;

FIG. 26 is a graphical representation showing a current densitydistribution indicating electron diffusion prevention in the imagedisplay device of FIG. 24;

FIG. 27 is a plan view showing a cathode substrate in a furtherembodiment of an image display device according to the presentinvention; and.

FIG. 28 is a sectional view showing a conventional image display devicein which a field emission element is incorporated.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, the present invention will be described hereinafter with referenceto accompanying drawings.

Referring first to FIGS. 24 to 26, an embodiment of an image displaydevice according to the present invention in which electron emittingelements are incorporated is illustrated.

An image display device of the first embodiment includes an anodesubstrate 302 and a cathode substrate 303 which are arranged in a mannerto be opposite to each and spaced from other at a predetermined intervaldefined therebetween, and side plates (not shown) arranged between theanode substrate 302 and the cathode substrate 303, which cooperate witheach other to form an envelope 304. The envelope 304 thus formed is thenevacuated to a high vacuum.

The anode substrate 302 has a light-permeable anode conductor 305 formedall over an inner surface thereof. The anode conductor 305 is providedthereon with phosphor layers 306 of desired luminous colors in adot-like or stripe-like manner, resulting in forming a display section307. The anode conductor 305 is provided on a portion thereof interposedbetween each adjacent two phosphor layers 306 with a light shieldingmask 308.

The cathode substrate 303 is formed thereof with a plurality ofstripe-like cathode conductors 309, which are arranged so as to extendin a direction perpendicular to a direction of arrangement of thephosphor layers 306 and in a manner to be divided for every picturecell. The cathode conductors 309 each are provided thereon with aninsulating layer 311 formed with openings 310. The openings 310 each areprovided therein an emitter electrode 312 of a conical shape acting asan electron emitter or electron emitting element while being arranged onthe cathode conductor 309.

The insulating layers 311 each are provided on an upper surface thereofwith gate electrodes 314 each formed with apertures 313 in a manner topositionally correspond to or be aligned with the openings 310. The gateelectrode 314 is formed into a stripe-like shape in a manner tocorrespond to each of the picture cells and arranged so as to extend ina direction parallel to the direction of arrangement of the phosphorlayers 306.

The image display device also includes a plurality of diffusionprevention electrodes 315 each arranged between each adjacent two of thegate electrodes 314 in a stripe-like manner. The diffusion preventionelectrodes 315 are electrically connected common to each other and eachhave a voltage lower than a section voltage applied to the gateelectrodes constantly applied thereto.

FIG. 26 shows a relationship between a voltage applied to the diffusionprevention electrodes 315 and spreading of electrons, which is obtainedwhen a gap defined between the gate electrode 314 and the phosphor 306is set to be 150 um and the gate electrode 314 is formed into a width of80 um. Also, a distance between the gate electrode 314 and the diffusionprevention electrode 315 is set to be 10 um and the diffusion preventionelectrode 315 is formed into a width of 20 um. Further, the gateelectrodes 314 each have a voltage of 120 V applied thereto and theanode conductor 305 of the display section 307 has a voltage of 800 Vapplied thereto. FIG. 26 indicates a tendency that a decrease indiffusion prevention voltage relative to the gate voltage leads tofocusing of electrons.

Referring now to FIG. 27, a second embodiment of an image display deviceaccording to the present invention is illustrated, wherein each gateelectrode 314 to which the same voltage is applied is divided into aplurality of gate electrode elements 324. Also, a diffusion preventionelectrode 325 is arranged between each adjacent two of the gateelectrode elements 324 so as to extend therebetween. Such constructioncontributes to an increase in focusing of electrons.

In each of the embodiments described above, the gate electrodes 314 anddiffusion prevention electrodes 315 are formed into a stripe-like shapeand arranged so as to be parallel to each other. Alternatively, the gateelectrode and diffusion prevention electrode corresponding to the gateelectrode each are formed at at least a part thereof into a pectinateshape, so that both are combined together in a manner to bite each otherat predetermined intervals. Although in each of the first and secondembodiments described above, focusing of electrons is predominantlycarried out in a direction of width of the stripe, the configuration ofboth electrodes into a pectinate shape permits focusing of electrons tobe improved in two or more directions at the pectinate portion of thegate electrode surrounded by the pectinate portion of the diffusionprevention electrode.

In each of the embodiments described above, the diffusion preventionelectrodes each have a voltage constantly applied thereto.Alternatively, a voltage may be applied to the diffusion preventionelectrodes between which the the gate electrode is interposed, only whena selection voltage is applied to the gate electrode in synchronism withdriving of the gate electrode.

Referring now to FIG. 1, a third embodiment of an image display deviceaccording to the present invention is illustrated.

An image display device of the third embodiment includes a firstsubstrate 1 formed thereon with cathode electrodes 2 of a stripe-likeshape and gate electrodes 3 of a stripe-like shape. The gate electrodes3 are arranged on the cathode electrodes 2 through an insulating layerin a manner to be perpendicular to the cathode electrodes 2. The gateelectrodes 3 each are formed with openings 4 through which electronsfield-emitted from emitters formed on each of the cathode electrodes 2are discharged.

Reference numeral 5 designates gate lead-out electrodes (G1-Gm) led outof the gate electrodes 3, respectively, 6 designates cathode lead-outelectrodes (C1-Cn) led out of the cathode electrodes 2, and 7 is asecond substrate arranged opposite to the first substrate 1 and providedthereon with anode electrodes of a stripe-like shape. The anodeelectrodes includes first anode electrodes 8 of a stripe-like shape andsecond anode electrodes 9 of a stripe-like shape each arranged betweeneach adjacent two of the first anode electrodes 8. Reference numeral 10designates a first anode lead-out electrode (A1) led out of or connectedto each of the first anode electrodes and 11 is a second anode lead-outelectrode (A2) led out of or connected to each of the second anodeelectrodes 9. The stripe-like anode electrodes are provided thereon withphosphors R, G and B in turn and in a repeated manner.

Now, the manner of driving of the image display device of the thirdembodiment constructed as described above will be described hereinafter.

The first and second anode electrodes 8 and 9 are selected by the anodelead-out electrodes A1 and A2 for driving, respectively. The cathodeelectrodes 2 are selected in turn by scanning the cathode lead-outelectrodes C1 to Cn.

For purpose of selectively driving the anode electrodes 8, the cathodelead-out electrodes C1 to Cn are scanned in turn while keeping apositive anode voltage applied to the anode lead-out electrode A1,during which color data on an image signal are kept applied to the gatelead-out electrodes G1 to Gm in synchronism with or in correspondence toa timing of the scanning. This results in picture cells of the phosphorsprovided on the anode electrodes 8 being excited by electrons emittedfrom the cathode electrodes scanned, to thereby be subject luminouscontrol depending on the color data applied to the gate lead-outelectrodes G1 to Gm.

Then, after scanning of the cathode lead-out electrodes C1 to Cn iscarried out with respect to the last cathode lead-out electrode Cn, thepositive anode voltage is then applied to the anode lead-out electrodeA2. Subsequently, the cathode lead-out electrodes are scanned in turn inthe same manner as described above, during which color data are appliedto the gate lead-out electrodes G1 to Gm depending on theabove-described scan timing. This results in picture cells of thephosphors of the anode electrodes 9 being excited by electrons emittedfrom the cathode lead-out electrodes C1 to Cn scanned and subject toluminous control depending on the color data applied to the gatelead-out electrodes, so that one image or an image for one frame may bedisplayed on the image display device.

Referring now to FIGS. 2 to 4, modifications of the image display deviceof FIG. 1 is illustrated.

In FIGS. 2 to 4, reference 1 designates a first substrate, 2 isstripe-like cathode electrodes formed on the first substrate 1, 3 isstripe-like gate electrodes formed on the cathode electrodes 2 throughan insulator so as to extend in a direction perpendicular to the cathodeelectrodes 2, 6 is cathode lead-out electrodes led out of the cathodeelectrodes 2, 7 is a second substrate arranged opposite to the firstsubstrate 1, 8 is first stripe-like anode electrodes formed on thesecond substrate 7, 9 is second stripe-like anode electrodes eacharranged between each adjacent two of the first anode electrodes 8, 10is a first anode lead-out electrode (A1) led out of each of the firstanode electrodes 8, and 11 is a second anode lead-out electrode (A2) ledout of each of the second anode electrodes 9.

Also, reference numeral 12 designates emitter arrays formed on each ofthe cathode electrodes 2 by integration techniques and each including aplurality of emitters of a conical shape for field-emitting electronstherefrom. 13 is spacers arranged between the first substrate 1 and thesecond substrate 7 for supporting the substrates in a manner to bespaced from each other at a predetermined interval. 14 is controlelectrodes each arranged between each adjacent two of the gateelectrodes 3, and 15 is a lead-out electrode led out from each of thecontrol electrodes 14 and serving to a control voltage to the controlelectrodes 14.

In the image display device of FIG. 2, the stripe-like anode electrodes3 are formed in a relationship of 1:1 to the first and second anodeelectrodes 8 and 9. A result of simulation of a current densitydistribution obtained by the image display device shown in FIG. 2 isindicated at reference character A in FIG. 5. It is known in the artthat electrons field-emitted from the emitter arrays 12 spread at anangle of about 30 degrees, therefore, it is considered that theelectrons reach the anode electrodes 8 and 9 while considerablyspreading from an end of each of the gate electrodes 3, during which thecurrent density distribution indicated at A in FIG. 5 is formed.

Now, driving for exciting the phosphors deposited on only one anodeelectrodes of the anode electrodes 8 and 9 will be describedhereinafter.

Supposing that the phosphors are formed into a width of 80 um at pitchesof 100 um on the abode electrodes 8 and 9, a positive anode voltage isapplied to only one anode electrodes of the anode electrodes 8 and 9 or,for example, only the anode electrodes 8 and a negative anode voltage isapplied to the other anode electrodes or the anode electrodes 9. Thisresults in electrons being repelled by the anode electrodes 9 becausethe negative voltage is kept applied to the anode electrodes 9, so thatonly the phosphors deposited on the anode electrodes 8 are excited forluminescence or light emission.

Application of the anode voltages to the anode electrodes 8 and 9 in amanner contrary to the above permits the phosphors deposited on only theanode electrodes 9 to be excited for light emission or luminescence, tothereby prevent leakage luminescence due to spreading of electrons.

The image display device shown in FIG. 3 is so constructed that each onegate electrode 3 is arranged with respect to each one of the anodeelectrodes 8 and each one of the anode electrodes 9, thus, arelationship of the gate electrodes to the anode electrodes 8 and 9 is1:2. The device of FIG. 3 is likewise driven so that a positive anodevoltage is selectively applied to one of the anode lead-out electrodesA1 and A2 of the anode electrodes 8 and 9. Electrons emitted from theemitter arrays 12 are commonly fed to the anode electrodes 8 and 9 whilebeing controlled by the gate electrodes 3, therefore, application ofcolor data to the gate electrodes 3 in synchronism with changing-overbetween the anode electrodes 8 and 9 permits each one gate electrode 3to control light emission or luminescence of each one of the anodeelectrodes 8 and each one of the anode electrodes 9.

The image display device of FIG. 3 permits the anode lead-out electrodesA1 and A2 of the anode electrodes 8 and 9 to be arranged withoutmulti-level crossing of the electrodes A1 and A2. Also, the devicepermits arrangement of the gate electrodes and anode electrodes at arelationship of 1:2, to thereby substantially reduce a cost required fordriving the gate electrodes.

In view of the fact known in the art, it is considered that electronsfed from the emitter array 12 to one of the anode electrodes 8 selectedspread at an angle of about 30 degrees. This causes a part of theelectrons to be fed to the anode electrodes adjacent to the anodeelectrode selected as indicated at dotted lines in FIG. 5, leading toleakage of luminescence, resulting in the image display device failingto exhibit a display with high definition.

The image display device shown in FIG. 4 is constructed so as toeliminate the problem. For this purpose, the device of FIG. 4 is soconstructed that each one control electrode 14 is arranged between eachadjacent two of the gate electrodes 3. A result of simulation of acurrent density distribution obtained due to arrangement of the controlelectrodes 14 between the gate electrodes 3 is indicated at B in FIG. 5.It will be noted from the result that arrangement of the controlelectrodes 14 restrains spreading of electrons.

A result of simulation of an electric field distribution concurrentlyobtained is shown in FIG. 6, which indicates that electronsfield-emitted from the emitter array 12 are positively captured by onlyone anode electrode 8 without spreading, as indicated at broken lines.Thus, it will be noted that the image display device of FIG. 4effectively prevents leakage luminescence. In the device of FIG. 4, thecontrol electrodes 14 each have a negative voltage of a predeterminedlevel constantly applied thereto.

In the image display device shown in each of FIGS. 2 to 4, the first andsecond substrates may be optimumly formed of glass. Alternatively, thefirst substrate may be conveniently formed of silicon, germanium or thelike. The anode electrodes each may comprise a transparent electrodemade of a suitable transparent conductive material.

Now, a drive device for driving the image display device of FIG. 3 willbe described hereinafter with reference to FIG. 7 by way of example,which shows arrangement of the electrodes of the image display devicewhich is viewed from a side of the anode electrodes of the image displaydevice of FIG. 3.

In FIG. 7, the anode lead-out electrodes A1 and A2 are led out of theanode electrodes 8 and 9 in the lump in a manner to opposite to eachother, respectively. The gate electrodes 3 are arranged so as to bespaced from the anode electrodes 8 and 9 and parallel thereto. The gateelectrodes 3 has gate lead-out electrodes GT1, GT2, . . . , GTlconnected thereto or led out thereof, respectively. The gate electrodes3 each are arranged in a manner to straddle each of the anode electrodes8 and each of the anode electrodes 9 so that each emitter array forfield-emitting electrons is used common to each anode electrode 8 andeach anode electrode 9.

Also, the cathode electrodes 2 are arranged below the gate electrodes 3in a manner to be perpendicular to the anode electrodes 8 and 9 and thestripe-like cathode electrodes 2 have cathode lead-out electrodes C1,C2, . . . , Cn led out thereof, respectively. The cathode electrodes 2each are provided thereon with the emitter arrays.

Further, the anode electrodes 8 and 9 alternately arranged in a repeatedmanner are depositedly formed thereon with phosphors R, G and B in turnin a repeated manner, so that the phosphors positioned at intersectionsbetween the anode electrodes 8 and 9 and the cathode electrodes 2constitute picture cells, resulting in picture cells R11, G11 and B11;R21, G21 and B21; . . . .; Rm1, Rm2 and Bm1 thus formed cooperating toeach other to form first one line. Likewise, second one line is formedby picture cells R12, G12 and B12; . . . .; Rm2, Gm2 and Bm2 and lastone line is formed by R1n, G1n and B1n; . . . ; Rmn, Gmn, Bmn.

Thus, the picture cells R11 to Bmn provided on the anode electrodes 8and 9 are arranged in a matrix-like manner and selectively driven bymeans of the anode lead-out electrodes A1 and A2 and cathode lead-outelectrodes C1 to Cn.

Selection of the picture cells of the image display device of FIG. 3 bythe drive device constructed as described above is illustrated by way ofexample in each of FIGS. 10(a) to 10(d). Selection of picture cellsshown in each of FIGS. 10(a) to 10(d) is carried out for an image forone frame by scanning the cathode lead-out electrode C1 to Cn whilekeeping a positive anode voltage applied to the anode lead-out electrodeA1 and then scanning the cathode lead-out electrodes C1 to Cn whilekeeping the positive anode voltage applied to the anode lead-outelectrode A2.

In FIGS. 10(a) to 10(d), R, G and B indicate the picture cells of FIG. 7arranged in a matrix-like manner on the anode electrodes, of whichsuffixes are deleted for the sake of brevity. FIG. 10(a) shows a statethat picture cells selected by applying a positive anode voltage to theanode lead-out electrode A1 and selecting the cathode lead-out electrodeC1 are permitted to emit light. More particularly, in FIG. 10(a),phosphors R, B, G, . . . on a first line on which oblique lines aredrawn are permitted to emit light. The reason why picture cells arrangedat every second interval are thus permitted to emit light is that theanode lead-out electrode A1 is led out of the anode electrodes 8alternated with the anode electrodes 9. Light-emission or luminescenceof the picture cells thus selected is controlled depending on color dataconcurrently applied to the gate lead-out electrodes GT1 to GTl of thegate electrodes 3.

FIG. 10(b) shows a state obtained at a timing subsequent to the state ofFIG. 10(a). Application of the positive anode voltage to the anodelead-out electrode A1 is still kept, however, the cathode lead-outelectrode C2 is selected in place of the electrode C1. This results inpicture cells R, B, G . . . on a second line on which oblique lines aredrawn in FIG. 10(b) being selected and permitted to emit light. In FIG.10(b) as well as FIG. 10(a) described above, the picture cells arrangedat every other interval are permitted to emit light and luminescence ofthe picture cells is controlled by color data concurrently applied tothe gate lead-out electrodes GT1 to GTn.

Such driving is repeated, so that when the last cathode lead-outelectrode Cn is subject to scanning, the image display device takes sucha state as shown in FIG. 20(c). In FIG. 10(c), the positive anodevoltage is applied to the anode lead-out electrode A2 and the cathodelead-out electrode C1 is selected, so that picture cells are selectedand permitted to emit light.

In this state, picture cells G, R, B which correspond to the anodelead-out electrode A2 and are arranged at every other interval on thefirst line and on which oblique lines are drawn are permitted to emitlight and luminescence of the picture cells is controlled by color dataconcurrently applied to the gate lead-out electrodes GT1 to GTn. Thisresults in control of light emission or luminescence of all picturecells on the first line being completed.

Then, a state shown in FIG. 10(d) is obtained. In this state, thepositive anode voltage is kept applied to the anode lead-out electrodeA2 of the anode electrodes 9, however, the cathode lead-out electrode C2is selected in place of the cathode lead-out electrode C1, resulting inpicture cells being selected and permitted to emit light. Moreparticularly, picture cells G, R, B, . . . on the second line arepermitted to emit light and luminescence of the picture cells beingcontrolled by color data concurrently applied to the gate lead-outelectrodes GT1 to GTn.

Thus, the cathode lead-out electrodes C1 to Cn are scanned in turn whilethe positive anode voltage is kept applied to the anode lead-outelectrode A2, so that when the last cathode Cn is scanned, all picturecells of the display device are permitted to emit light and luminescenceof the picture cells is controlled, resulting in an image for one framebeing displayed on the display device.

The drive device for carrying out the driving and controlling describedabove will be more detailedly described with reference to FIGS. 8 and9(a) to 9(k), 9(m), 9(n) and 9(p).

In FIG. 8, reference numeral 50 designates an image display device (FED)which includes field emission cathodes including picture cells of m×n innumber arranged in a matrix-like manner, 51 is a clock generator forgenerating a clock in synchronism with a synchronous signal appliedthereto, 52 is a display timing control circuit for controlling adisplay timing by means of the clock generated by the clock generator51, 53 is a memory write control circuit for controlling writing of avideo memory 54 which includes frame memories or line memories 54-1,54-2 and 54-3 for storing data on R, G and B images therein, 55-1 to55-3 are buffer registers for holding therein data on luminous colors R,G and B read out from the-video memory 54.

Reference numeral 56 designates an address counter for generatingaddresses for the video memories 54, 57 is a color section circuit, 58is a shift register for shifting data for controlling the cathodeelectrodes, 59 is a latch circuit for latching data of the shiftregister 58, 60 is a cathode driver for driving the cathode electrodesby means of data of the latch circuit 59, 61 is a shift register forshifting color data fed from the buffer registers 55-1 to 55-3 by meansof a shift clock, 62 is a latch circuit for latching data of the shiftregister 61, and 63 is a gate driver for driving the gate electrodes bymeans of an output of the latch circuit 62.

FIG. 9(a) shows an output pulse of an anode driver for driving the anodelead-out electrode A1, FIG. 9(b) shows an output pulse of the anodedriver 64 for driving the anode lead-out electrode A2, FIG. 9(c) showsan output pulse of the cathode driver 60 for driving the cathodelead-out electrode C1, FIG. 9(d) shows an output pulse of the cathodedriver 60 for driving the cathode lead-out electrode C2, FIG. 9(e) showsan output pulse of the cathode driver 60 for driving the cathodelead-out electrode C3, and FIG. 9(f) shows an output pulse of thecathode driver 60 for driving the cathode lead-out electrode Cn.

Also, FIG. 9(g) shows color data applied from the gate driver 63 to thegate lead-out electrode GT1, FIG. 9(h) shows color data applied from thegate driver 63 to the gate lead-out electrode GT2, FIG. 9(i) shows colordata applied from the gate driver 63 to the gate lead-out electrode GT3,FIG. 9(j) shows color data applied from the gate driver 63 to the gatelead-out electrode GT2, FIG. 9(k) shows an enable signal for controllingoperation of the cathode driver 60, FIG. 9(m) shows a latch pulseindicating a latch timing of each of the latch circuits 59 and 62, FIG.9(n) shows a shift clock fed to the shift register 61, and FIG. 9(p)shows color data fed from the gate driver 63 to the gate lead-outelectrodes GT1 to GTn of the gate electrode.

Now, the manner of operation of the drive device for the image displaydevice 50 constructed as described above will be described withreference to FIGS. 9(a) to 9(k), 9(m), 9(n) and 9(p).

Image data are fed to the memory write control circuit 53, in which awrite timing of the image data is subject to control. Also, the colordata are stored for every color in synchronism with a clock generated bythe clock generator in the video memory 54. The memories 54-1 to 54-3 ofthe video memory 54 have color data on the colors R, G and B storedtherein respectively. The color data thus stored in the memories areread therefrom depending on the addresses of the address counter 56while being subject to control by the color section circuit 57 and thenheld in the buffer registers 55-1 to 55-3.

The buffer registers 55-1, 55-2 and 55-3 are subject at an output timingthereof to control by the color selection circuit 57, so that the colordata held therein are fed in the same order as the picture cells R, Gand B shown in FIG. 10 to the shift register circuit 61. The shiftregister 61 shifts the color data by means of the shift clock SCLK shownin FIG. 9(n).

Of the picture cells on the first line of the image display device 50,color data of half picture cells corresponding in number to thestripe-like anode electrodes connected to the anode lead-out electrodeA1 are fed to the shift register 61, which then shifts color data on thepicture cells. Then, the color data are latched by the latch pulse shownin FIG. 9(m) in the latch circuit 62. Output data of the latch circuit62 are applied to the gate driver 63.

The display control timing circuit 52 controls the anode driver 64, tothereby cause the anode driver 64 to apply a positive anode voltage toonly the anode lead-lead electrode A1 as shown in FIG. 9(b). Also, thedisplay control timing circuit 52 feeds the shift register 58 with thelatch pulse shown in FIG. 9(m) as a shift pulse, resulting in a scansignal output from the control circuit 52 being shifted. An output ofthe shift register 58 is latched by the above-described latch pulse inthe latch circuit 59, so that the latch circuit 59 outputs the scansignal shifted at every latch pulse. The scan signal shifted is then fedto the cathode driver 60.

This results in output pulses being fed from the cathode driver 60 tothe cathode lead-out electrodes C1, C2, C3, . . . , Cn of the imagedisplay device 50 in turn as shown in FIGS. 9(c), 9(d), 9(e) and 9(f),so that the cathode lead-out electrodes C1, C2, C3, . . . , Cn each arescanned at a timing of the latch pulse described above.

At this time, color data shown in FIG. 9(g), 9(h), 9(i) and 9(j) are fedfrom the gate driver 63 to the gate lead-out electrodes GT1 to GTl insynchronism with scanning of the cathode lead-out electrodes C1 to Cn,so that color data on the colors R, B, G, . . . , G shown in FIG. 10(a)are fed to the gate lead-out electrodes GT1 to GTl while the cathodelead-out electrode C1 is kept driven as shown in FIG. 9(c).

Thus, half of the picture cells on the first line of the image displaydevice 50 are subject to luminous control as shown in FIG. 10(a). Then,the cathode lead-out electrode C2 is selected at a timing of the nextlatch pulse. At this time, the next color data have been shifted to theshift register 61 by means of the shift clock SCLK, so that the imagedisplay device 50 controls luminescence or light emission of half of thepicture cells on the second line as shown in FIG. 10(b).

Such scanning as described above is successively carried out, so thatscanning of the last cathode lead-out electrode C2 leads to control ofluminescence of half of the picture cells for one frame. Then, thedisplay timing control circuit 52 controls the anode driver 64,resulting in the anode driver 64 applying a positive anode electrode tothe anode lead-out electrode A2.

Then, scanning of the cathode lead-out electrodes C1 to Cn in the samemanner as described above causes the remaining half of the picture cellsfor one frame to be subject luminous control as shown in FIG. 10(c) and10(d), so that scanning of the last cathode lead-out electrode Cnresults in an image for one frame being displayed on the image displaydevice 50.

Thus, the drive device for the image display device 50 permits thenumber of times of changing-over between the anode lead-out electrodesfor every one frame to be only two, so that a drive circuit for theanode lead-out electrodes may be simplified in construction. Also,biasing of the anode electrodes which are not selected to a negativevoltage more effectively prevents color mixing.

Now, another embodiment of the drive device for the image display device50 will be described hereinafter with reference to FIGS. 11 to 13(d).

A drive device of the embodiment is adapted to carry out selection ofthe anode lead-out electrode A1 and application of a positive anodevoltage to the anode lead-out electrode A1 and then carry out selectionof the anode lead-out electrode A2 and application of the positive anodevoltage to the anode lead-out electrode A2 while keeping the cathodelead-out electrode C1 selected. Then, the cathode lead-out electrode C2is selected in place of the cathode lead-out electrode C1. Also, theanode lead-out electrode electrode A1 is selected and then the anodelead-out electrode A2 is selected at the next timing while the cathodelead-out electrode C2 is kept selected. This results in an image for oneframe being obtained on the image display device at the time whenselection of the last cathode lead-out electrode Cn is completed.

Now, the manner of operation of the drive device will be described withreference to FIGS. 13(a) to 13(d).

In FIG. 13(a) to 13(d), R, G and B designate the picture cells of FIG. 7arranged in a matrix-like manner on each of the anode electrodes, ofwhich suffixes are deleted for the sake of brevity. FIG. 13(a) shows astate that picture cells selected by applying a positive anode voltageto the anode lead-out electrode A1 selected and selecting the cathodelead-out electrode C1 are permitted to emit light. More particularly, inFIG. 13(a), half of phosphors R, B, G, . . . on a first line whichcorrespond to the anode lead-out electrode A1 and on which oblique linesare drawn are permitted to emit light. The reason why the picture cellsarranged at every other or second interval are thus permitted to emitlight is that the anode electrodes 8 connected to the anode lead-outelectrode A1 are arranged at every second interval or alternated withthe anode electrodes 9. Light-emission or luminescence of the picturecells thus selected is controlled depending on color data concurrentlyapplied to the gate lead-out electrodes GT1 to GTl of the gateelectrodes 3.

FIG. 13(b) shows a state obtained at a timing subsequent to the state ofFIG. 13(a). In the state shown in FIG. 13(b), the anode lead-outelectrode A2 is selected and applied thereto a positive anode voltagewhile the cathode lead-out electrode C1 is kept selected. Picture cellsthus selected are shown in FIG. 13(b). More particularly, picture cellsR, B, G, . . . arranged at every other interval on the first line onwhich oblique lines are drawn are permitted to emit light. Luminescenceof the picture cells thus permitted to emit light is controlled by colordata concurrently applied to the gate lead-out electrodes GT1 to GTn, sothat all the picture cells on the first line is subject to luminouscontrol.

Then, the cathode lead-out electrode C2 is selected at the next timingand the anode lead-out electrode A1 is selected, followed by applicationof a positive anode voltage to the anode lead-out electrode A1. FIG.13(c) shows picture cells thus selected. More particularly, half R, B,G, . . . of picture cells on a second line which are arranged at everyother interval and on which oblique lines are drawn are permitted toemit light and luminescence of the picture cells selected is controlledby color data concurrently applied to the gate lead-out electrodes GT1to GTn.

Then, a state shown in FIG. 13(d) is obtained at the next timing, inwhich a positive anode voltage is applied to the anode lead-outelectrode A2 while the cathode lead-out electrode C2 is kept selected.This results in the remaining picture cells G, R, B, . . . on the secondline being permitted to emit light and luminescence of the picture cellsbeing controlled by color data concurrently applied to the gate lead-outelectrode GT1 to GTn of the gate electrodes 3.

Thus, the anode lead-out electrodes A1 and A2 are selected in turn whilethe cathode lead-out electrodes C1 to Cn are scanned in turn, so thatscanning of the last cathode lead-out electrode Cn results in all thepicture cells being permitted to emit light and luminescence thereofbeing controlled. Thus, an image for one frame is displayed on the imagedisplay device.

Construction of the drive device which drives and controls the imagedisplay device as described above will be described with reference toFIG. 11 and 12(a) to 12(k), 12(m), 12(n) and 12(p).

In FIG. 11, reference numeral 50 designates the image display device(FED) constructed as described above which is driven and controlled bythe drive device. The image display device, as described above, includesthe field emission cathodes including the picture cells of m×n in numberarranged in a matrix-like manner. In the device shown in FIG. 11,reference numeral 51 is a clock generator for generating a clock insynchronism with a synchronous signal applied thereto, 52 is a displaytiming control circuit for controlling a display timing by means of theclock generated by the clock generator 51, 53 is a memory write controlcircuit for controlling writing of a video memory 54 which includesframe memories or line memories 54-1, 54-2 and 54-3 for storing data onR, G and B images therein, 55-1 to 55-3 are buffer registers for holdingtherein data on luminous colors R, G and B read out from the videomemory 54.

Reference numeral 56 designates an address counter for generatingaddresses for the video memories 54, 57 is a color section circuit, 58is a shift register for shifting data for scanning and controlling thecathode electrodes, 59 is a latch circuit for latching data of the shiftregister 58, 60 is a cathode driver for driving the cathode electrodesby means of data of the latch circuit 59, 61 is a shift register forshifting color data fed from the buffer registers 55-1 to 55-3 by meansof a shift clock SCLK, 62 is a latch circuit for latching data of theshift register 61, and 63 is a gate driver for driving the gateelectrodes by means of an output of the latch circuit 62.

FIG. 12(a) shows a drive pulse of an anode driver 64 for driving theanode lead-out electrode A1, FIG. 12(b) shows a drive pulse of the anodedriver 64 for driving the anode lead-out electrode A2, FIG. 12(c) showsa drive pulse of the cathode driver 60 for driving the cathode lead-outelectrode C1, FIG. 12(d) shows a drive pulse of the cathode driver 60for driving the cathode lead-out electrode C2, FIG. 12(e) shows a drivepulse of the cathode driver 60 for driving the cathode lead-outelectrode C3, and FIG. 12(f) shows a drive pulse of the cathode driver60 for driving the cathode lead-out electrode Cn.

FIG. 12(g) shows color data applied from the gate driver 63 to the gatelead-out electrode GT1, FIG. 12(h) shows color data applied from thegate driver 63 to the gate lead-out electrode GT2, FIG. 12(i) showscolor data applied from the gate driver 63 to the gate lead-outelectrode GT3, FIG. 12(j) shows color data applied from the gate driver63 to the gate lead-out electrode GT1, FIG. 12(k) shows an enable signalfor controlling operation of the cathode driver 60, FIG. 12(m) shows alatch pulse for controlling the anode driver 64 which indicates a latchtiming of the latch circuit 62, FIG. 12(n) shows a shift clock fed tothe shift register 61, and FIG. 12(p) shows color data fed from the gatedriver 63 to the gate lead-out electrodes GT1 to GTn of the gateelectrode 3.

Now, the manner of operation of the drive device for the image displaydevice 50 constructed as described above will be described withreference to FIGS. 12(a) to 12(k), 12(m), 12(n) and 12(p).

Image data are fed to the memory write control circuit 53, in which awrite timing of the image data is subject to control. Also, the colordata are stored for every color in synchronism with a clock generated bythe clock generator in the video memory 54. The memories 54-1 to 54-3 ofthe video memory 54 have color data on the colors R, G and B storedtherein respectively. The color data thus stored in the memories areread therefrom depending on the addresses of the address counter 556while being subject to the color section circuit 57 and then held in thebuffer registers 55-1 to 55-3.

The buffer registers 55-1, 55-2 and 55-3 are subject at an output timingthereof to control by the color selection circuit 57, so that the colordata held therein are fed in the same order as the picture cells R, Gand B shown in FIG. 10 to the shift register circuit 61. The shiftregister 61 shifts the color data by means of the shift clock SCLK shownin FIG. 12(n).

Of the picture cells on the first line of the image display device 50,half corresponding in number to the stripe-like anode electrodesconnected to the anode lead-out electrode A1 are fed to the shiftregister 61, which then shifts color data on the picture cells. Then,the color data are latched by the latch pulse shown in FIG. 12(m) in thelatch circuit 62. Output data of the latch circuit 62 are applied to thegate driver 63.

The display control timing circuit 52 applies the above-described latchpulse to the anode driver 64, to thereby alternately change over theanode lead-out electrode A1 and A2 in synchronism with the latch pulseas shown in FIG. 12(a) and 12(b), resulting in applying a positive anodevoltage to the anode lead-out electrode selected.

Also, the display control timing circuit 52 feed the shift register 58with a latch pulse of a cycle twice as long as that of the latch pulseshown in FIG. 12(m) as a shift pulse, resulting in a scan signal outputfrom the control circuit 52 being shifted. An output of the shiftregister 58 is latched by the above-described latch pulse of the doublecycle in the latch circuit 59, so that the latch circuit 59 outputs thescan signal shifted at every latch pulse. The scan signal shifted isthen fed to the cathode driver 60.

This results in output pulses being fed from the cathode driver 60 tothe cathode lead-out electrodes C1, C2, C3, . . . , Cn of the imagedisplay device 50 in turn as shown in FIGS. 12(c), 12(d), 12(e) and12(f), so that changing-over between the anode lead-out electrode A1 andthe anode lead-out electrode A2 is carried out for selection while thecathode lead-out electrodes C1, C2, C3, . . . , Cn each are selected inturn.

Concurrently, color data shown in FIG. 12(g), 12(h), 12(i) and 12(j) arefed from the gate driver 63 to the gate lead-out electrodes GT1 to GTlin synchronism with changing-over between the anode lead-out electrodes,so that color data on the colors R, B, G, . . . , G shown in FIG. 13(a)are fed to the gate lead-out electrodes GT1 to GTl while the anodelead-out electrode A1 is kept driven as shown in FIG. 12(a).

Thus, half of the picture cells on the first line of the image displaydevice 50 on which oblique lines are drawn is subject to luminouscontrol as shown in FIG. 13(a). Then, the anode lead-out electrode A2 isselected at a timing of the next latch pulse. At this time, the nextcolor data have been shifted to the shift register 61 by means of theshift clock SCLK, so that the image display device 50 controlsluminescence or light emission of the remaining picture cells on thefirst line on which oblique lines are drawn in FIG. 13(b).

Then, scanning is carried out while keeping the cathode lead-out C2selected and carrying out changing-over between the the anode lead-outelectrodes, so that picture cells on a second line being subject toluminous-control as shown in FIGS. 13(c) and 13(d).

Such operation is successively repeated; so that when scanning of thelast cathode lead-out electrode is carried out, picture cells on alllines are subject to luminous control, resulting in an image for oneframe being displayed on the image display device.

The picture cells on the image display device may be scanned in a zigzagmanner depending on a manner of scanning of the anode lead-outelectrodes and cathode lead-out electrodes. Also, the embodimentsdescribed above each have the phosphors of red, blue and green luminouscolors incorporated therein. Alternatively, the present invention may beconstructed in such a manner that one kind of a phosphor having anincreased luminous wavelength range and filters different intransmission wavelength characteristics are arranged, to thereby obtaina plurality of luminous colors such as red, blue, green and the likethrough the filters.

Now, a further embodiment of an image display device according to thepresent invention in which arrangement of anode electrodes which areexpected to be decreased in luminance and arrangement of emitter arraysare specified will be described hereinafter with reference to FIGS. 14and 15. The embodiment is adapted to obtain red, blue and green luminouscolors by phosphors themselves without using any filter. In FIGS. 14 and15, reference numeral 201 designates a first substrate made of amaterial such as glass or the like on which FED arrays are arranged, 202are cathode electrodes formed on the first substrate 201, 203 is a gateelectrode means including a plurality of stripe-like gate electrodes203-1, 203-2 . . . formed through an insulating film such as a SiO₂ filmor the like on each of the cathode electrodes 202, and 204 is an emittermeans including emitter arrays 204-1, 204-2 . . . for field-emittingelectrons which are formed on each of the cathode electrodes 202 in amanner to positionally correspond to the gate electrodes 203-1, 203-2 .. . .

Reference numeral 205 designates a second substrate made of glass or thelike and arranged so as to be spaced at a predetermined distance fromthe first substrate 201, and 206 is an anode electrode means including aplurality of anode electrodes 206-1, 206-2 and 206-3, which are formedof transparent conductive material. The anode electrodes 206-1, 206-2and 206-3 are formed thereon with phosphors of a green luminous color, ared luminous color and a blue luminous color, respectively. Referencenumeral 207 designates control electrodes arranged between the gateelectrodes 203 for restraining spreading of electrodes.

In view of the fact that a current technical level fails to permit aphosphor of a red luminous color to exhibit luminous efficiency of alevel equal to that of phosphors of the other luminous colors, thephosphor of a red luminous color is arranged on the anode electrode206-2.

Also, reference numeral 208 designates a switch (SW) for selectivelyscanning the anode lead-out electrodes A1 and A2 of the anode electrodemeans 206, 209 is an anode voltage (Ea) applied to the anode electrodesselected, 210 is a negative voltage (Ec) applied to the controlelectrodes 207, A1 is an anode lead-out electrode to which the anodeelectrode 206-2 having the phosphor of a red luminous color depositedthereon is connected, A2 is an anode lead-out electrode to which theanode electrodes 206-1 and 206-2 having the phosphors of blue and redluminous colors deposited thereon are connected, and GT1 and GT2 aregate lead-out electrodes led out of the gate electrodes 203-1 and 203-2,respectively. The FEC arrays each are constituted by the cathodeelectrodes 202, gate electrodes 203 and emitters 204.

As shown in FIGS. 14 and 15, the gate electrodes 203-1 and 203-2 arepositioned below the anode electrode 206-2, the gate electrode 203 ispositioned below the anode electrode 206-1, and the gate electrode 203-2is located below the anode electrode 206-3.

Then, when the switch 208 is changed over as shown in FIG. 14, the anodevoltage 209 is applied to the anode lead-out electrode A1, resulting inbeing applied to the anode electrode 206-2 provided thereon with thephosphor of a red luminous color. This causes electrons emitted from theemitter arrays 204-1 and 204-2 to be captured by the anode electrode206-2 as shown in FIG. 14, so that the phosphor of a red luminous colordeposited on the anode electrode 206-2 may be excited for light emissionor luminescence. Concurrently, color data are applied to the gatelead-out electrodes GT1 and GT2, to thereby control the gate electrodes203-1 and 203-2.

Subsequently, the switch 208 is changed over as shown in FIG. 15, theanode electrode 209 is then applied to the anode lead-out electrode A2,to thereby be applied to the anode electrode 206-1 having the phosphorof a green luminous color deposited thereon and the anode electrode206-3 including the phosphor of a blue luminous color. This causeselectrons emitted from the emitter array 204-1 to be captured by theanode electrode 206-1 and electrons emitted from the emitter array 204-2to be captured by the anode electrode 206-3, so that the phosphors ofgreen and blue luminous colors deposited on the anode electrodes may beexcited for luminescence. Concurrently, color data on a green luminouscolor are applied to the gate lead-out electrode GT1 and those on a blueluminous color are applied to the gate lead-out electrode GT2, so thatthe gate electrodes 203-1 and 203-2 are controlled.

In view of the fact that such an FEC as shown in FIG. 13 causeselectrons to be emitted from an emitter of a conical shape whilespreading at an angle of about 30 degrees, it would be considered thatthe image display device shown in FIG. 14 has a possibility thatelectrons emitted from the emitter arrays 204-1 and 204-2 are partiallycaptured by the anode electrodes 206-3 and 206-1, respectively, asindicated at broken lines in FIG. 15.

In order to eliminate the problem, the control electrode 207 is arrangedbetween each adjacent two of the gate electrodes 203 and the negativecontrol voltage Ec is applied thereto. An electric field distributionobtained due to application of the negative voltage Ec to the controlelectrodes 207 is shown in each of FIGS. 16(a) and 16(b). Moreparticularly, FIG. 16(a) shows an electric field distribution obtainedby the device shown in FIG. 14 and FIG. 16(b) shows that by the deviceof FIG. 15. When the anode electrode 206-2 is selected and the anodevoltage Ea is applied thereto as shown in FIG. 14, electrons emittedfrom portions of the emitter arrays 204-1 and 204-2 at which the gateelectrodes 203-1 and 203-2 are arranged are deflected toward the anodeelectrode 206-2 by the electric field shown in FIG. 16(a). When theanode electrodes 206-1 and 206-3 are selected and the anode voltage Eais applied thereto as shown in FIG. 15, the electric field shown in FIG.16(b) causes electrons emitted from a portion of the emitter array atwhich the gate electrode 203-1 is arranged to be deflected toward theanode electrode 206-1 and those emitted from a portion of the emitterarray 204-2 at which the gate electrode 203-2 is arranged to bedeflected toward the anode electrode 206-3.

Concurrently, the negative control voltage Ec is kept applied to thecontrol electrodes 207, which voltage generates an electric field whichpermits electrons emitted from the emitter arrays to be attracted by thecorresponding anode electrodes while preventing the electrons from beingattracted by the adjacent anode electrodes as broken lines in FIG. 15.

FIG. 17 shows arrangement of the electrodes of each of the image displaydevices shown in FIGS. 14 and 15 which is viewed from a side of theanode electrodes, wherein the control electrodes are omitted for thesake of brevity. In FIG. 17, the anode electrode 206-2 is connected tothe anode lead-out electrode A1 led out of one side and the anodeelectrodes 206-1 and 206-3 are connected to the anode lead-out electrodeA2 led out of the other or opposite side. The gate electrodes 203-1,203-2, . . . , 203-1 are arranged in a manner to be spaced from theanode electrodes 206-1 to 206-3 and parallel thereto and the gatelead-out electrodes GT1, GT2, . . . , GTl are led out of the gateelectrodes 203-1 to 203-1, respectively. The gate electrode 203-1 isarranged so as to straddle or extend over the anode electrodes 206-1 and206-2 and the gate electrode 203-2 is arranged so as to straddle theanode electrode 206-2 and 206-3.

Also, the cathode electrodes 202 are arranged below the gate electrodes203-1 to 203-1 so as to be perpendicular to the anode electrodes 206-1to 206-3 and the cathode lead-out electrodes C1, C2, . . . , Cn are ledout of the stripe-like cathode electrodes 202, respectively. The emitterarrays are formed on the cathode electrodes 202. The anode electrodes206-1 to 206-3 are depositedly formed thereon with the phosphor layersof green, red and blue luminous colors in turn and in a repeated manner,so that the phosphors positioned at intersections between the anodeelectrodes 206-1 to 206-3 and the cathode electrodes 202 define picturecells G11, R11, B11, G21, R21, B21, . . . , Gm1, Rm1, Bm1 on a firsthorizontal line, picture cells G12, R12, B12, . . . , Gm2, Rm2, Bm2 on asecond horizontal line, . . . , picture cells G1n, R1n, B1n, . . . ,Gmn, Rmn, Bmn on the last horizontal line.

Thus, the picture cells G11 to Bmn are arranged in a matrix-like mannerand selectively driven by the anode lead-out electrodes A1 and A2 andcathode lead-out electrodes C1 to Cn.

Now, an image display drive circuit for the image display device ofwhich the electrodes are arranged as shown in FIG. 17 will beexemplified hereinafter. The circuit may be constructed in substantiallythe same manner as that shown in FIG. 11 but is somewhat differenttherefrom in timing as shown in FIG. 18.

The drive circuit is so constructed that selection of the anode lead-outelectrode A1 and application of the positive anode voltage Ea to theanode electrode 206-2 are carried out while keeping the cathode lead-outelectrode C1 selected and then selection of the anode lead-out electrodeA2 and application of the positive anode voltage to the anode electrodes206-1 and 206-3 are carried out at the next timing. Then, the anodelead-out electrode A1 is selected while keeping the cathode lead-outelectrode C2 selected in place of the cathode lead-out electrode C1 andthen the anode lead-out electrode A2 is selected at the next timing.Such operation is repeated successively, so that completion of selectionof the last cathode lead-out electrode Cn results in an image for oneframe being obtained on the image display device.

Now, the manner of operation of the drive circuit will be describedhereinafter with reference to FIGS. 19(a) to 19(d).

In FIG. 19(a) to 19(d), R, G and B designate the picture cells of FIG.17 arranged in a matrix-like manner on each of the anode electrodes206-1, 206-2 and 206-3, of which suffixes are deleted for the sake ofbrevity. FIG. 19(a) shows a state that picture cells selected byapplying a positive anode voltage to the anode electrode 206-2 selectedand selecting the cathode lead-out electrode C1 are permitted to emitlight. More particularly, in FIG. 19(a), phosphors of a red luminouscolor or phosphors R on a first line which are deposited on the anodeelectrode 206-2 and on which oblique lines are drawn are permitted toemit light. The reason why the picture cells or phosphors R arranged atevery third intervals are thus permitted to emit light is that the anodeelectrodes 206-2 connected to the anode lead-out electrode A1 arearranged at every third intervals. Light-emission or luminescence of thephosphors R thus selected is controlled depending on color data on a redluminous color concurrently applied to the gate lead-out electrodes GT1to GTl.

FIG. 19(b) shows a state obtained at a timing subsequent to the state ofFIG. 19(a). In the state shown in FIG. 19(b), the anode lead-outelectrode A2 is selected and a positive anode voltage is applied to theanode electrodes 206-1 and 206-3 while the cathode lead-out electrode C1is kept selected. Picture cells thus selected are permitted to emitlight. More particularly, the remaining phosphors G, B, G, B, . . . onthe first line on which oblique lines are drawn are permitted to emitlight. Concurrently, light emission of the first phosphor G on the firstline which is permitted to emit light is controlled by color data ongreen concurrently applied to the gate lead-out electrode GT1 and thatof the phosphor B next but one is controlled by color data on blueapplied to the gate lead-out electrode GT2. This results in-lightemission of all picture cells on the first line being controlled.

Then, at the next timing, the cathode lead-out electrode C2 is selectedand the anode lead-out electrode A1 is selected, followed by applicationof the positive anode voltage Ea to the anode electrode 206-2, resultingin picture cells shown in FIG. 19(c) being selected. More particularly,phosphors R on a second line on which oblique lines are drawn arepermitted to emit light and luminescence of the phosphors R selected iscontrolled by color data on red concurrently applied to the gatelead-out electrodes GT1 to GTl.

Subsequently, a state shown in FIG. 19(d) is obtained at the nexttiming, in which the positive anode voltage Ea is applied to the anodeelectrodes 206-1 and 206-3 while the anode lead-out electrode A2 is keptselected. Concurrently, the cathode lead-out electrode C2 is still keptselected. This results in the remaining phosphors G, B, G, B, . . . onthe second line being permitted to emit light, and luminescence of thephosphors is controlled by color data on green or blue concurrentlyapplied to the gate lead-out electrode GT1 to GTn.

Thus, the anode lead-out electrodes A1 and A2 are selected in turn whilethe cathode lead-out electrodes C1 to Cn are scanned in turn, so thatscanning of the last cathode lead-out electrode Cn results in all thepicture cells of the image display device being permitted to emit lightand luminescence thereof being controlled. Thus, an image for one frameis displayed on the image display device.

Now, the manner of operation of the drive circuit for the image displaydevice 50 constructed as described above will be described withreference to FIGS. 5 and 18(a) to 18(k), 18(m), 18(n), 18(p) 18(q)

Image data are fed to the memory write control circuit 53, in which awrite timing of the image data is subject to control. Also, the colordata are stored for every color in the video memory 54 in synchronismwith a clock generated by the clock generator. The memories 54-1 to 54-3of the video memory 54 have color data on the colors R, G and B storedtherein respectively. The color data thus stored in the memories areread therefrom depending on the addresses of the address counter 56while being subject to control by the color section circuit 57 and thenheld in the buffer registers 55-1 to 55-3.

The buffer registers 55-1, 55-2 and 55-3 are subject at an output timingthereof to control by the color selection circuit 57, so that color datacorresponding to picture cells for every line on which oblique lines aredrawn in FIGS. 19(a) to 19(d) are fed from the buffer registers to theshift register circuit 61. The shift register 61 shifts the color databy means of a shift clock SCLK shown in FIG. 18(n).

After color data corresponding in number to the above-described picturecells for one line on which oblique lines are drawn are shifted by theshift register 61, the color data are latched by a latch pulse shown inFIG. 18(m) in the latch circuit 62. Output data of the latch circuit 62are applied to the gate driver 63.

The display control timing circuit 52 applies, to the anode driver 64,the latch pulse to the latch circuit 63 to control the anode lead-outelectrode A1 and anode lead-out electrode A2 in a manner to alternatelychange over them in synchronism with the latch pulse as shown in FIGS.18(a) and 18(b), to thereby cause a positive anode voltage Ea to beapplied to the anode lead-out electrode selected.

Also, the display control timing circuit 52 feeds the shift register 58with a latch pulse shown in FIG. 18(q) of a cycle twice as long as thelatch pulse shown in FIG. 18(m) as a shift pulse, resulting in a scansignal output from the control circuit 52 being shifted. An output ofthe shift register 58 is latched by the above-described double latchpulse in the latch circuit 59, so that the latch circuit 59 outputs thescan signal shifted at every latch pulse. The scan signal shifted isthen fed to the cathode driver 60.

This results in the cathode driver 60 selecting the cathode lead-outelectrodes C1, C2, C3, . . . , Cn of the image display device 50 in turnas shown in FIGS. 18(c), 18(d), 18(e) and 18(f), during whichchanging-over between the anode lead-out electrode A1 and the anodelead-out electrode A2 is carried out for selection.

Concurrently, color data shown in FIG. 18(g), 18(h), 18(i) and 18(j) arefed from the gate driver 63 to the gate lead-out electrodes GT1 to GTlin synchronism with changing-over between the anode lead-out electrodes,so that color data on the colors R, R, R, . . . , R shown in FIG. 19(a)are fed to the gate lead-out electrodes GT1 to GTl while the anodelead-out electrode A1 is kept driven as shown in FIG. 18(a).

Thus, of the picture cells on the first line of the image display device50, the picture cells R on which oblique lines are drawn are subject toluminous control as shown in FIG. 19(a). Then, the anode lead-outelectrode A2 is selected at a timing of the next latch pulse. At thistime, color data on green and blue have been shifted in the shiftregister 61 by means of the shift clock SCLK, so that the image displaydevice 50 controls luminescence or light emission of the remainingpicture cells G and B on the first line shown in FIG. 19(b) on whichoblique lines are drawn.

Then, the cathode lead-out electrode C2 is selected at the next timingand changing-over between the anode lead-out electrodes A1 and A2 iscarried out, so that light emission of picture cells on a second lineare controlled.

Such operation is repeated in turn, so that when scanning of the lastcathode lead-out electrode Cn is completed, picture cells on all linesare subject to luminous control, resulting in an image for one framebeing displayed on the image display device 50.

Now, another example of the drive circuit for driving the image drivedevice 50 will be described. The drive circuit may be basicallyconstructed in substantially the same manner as that shown in FIG. 8,although both are somewhat different in timing.

As shown in FIGS. 20(a) to 20(k), 20(m), 20(n) and 20(p), the cathodelead-out electrodes C1 to Cn are scanned in turn while a positive anodevoltage Ea is kept applied to the anode lead-out electrode A1. Aftercompletion of scanning of the cathode lead-out electrodes, the cathodelead-out electrodes C1 to Cn are scanned in turn while the positiveanode voltage is kept applied to the anode lead-out electrode A2,resulting in an image for one frame being obtained.

FIGS. 21(a) to 21(d) show scanning of picture cells.

In FIGS. 21(a) to 21(d), R, G and B designate the picture cells of FIG.17 arranged in a matrix-like manner on each of the anode electrodes, ofwhich suffixes are deleted for the sake of brevity. FIG. 21(a) shows astate that picture cells selected by applying a positive anode voltageEa to the anode lead-out electrode A1 and selecting the cathode lead-outelectrode C1 are permitted to emit light, wherein the selected picturecells are indicated at oblique lines. More particularly, in FIG. 21(a),phosphors of a red luminous color or phosphors R, R, . . . on a firstline which are deposited on the anode electrode 206-2 connected to theanode lead-out electrode A1 and on which oblique lines are drawn arepermitted to emit light. The reason why the picture cells or phosphors Rarranged at every third intervals are thus permitted to emit light isthat the anode electrodes 206-2 are arranged at every third intervals.Light emission or luminescence of the phosphors R thus selected iscontrolled depending on color data on a red luminous color concurrentlyapplied to the gate lead-out electrodes GT1 to GTl.

FIG. 21(b) shows a state obtained at a timing next to the state shown inFIG. 21(a0, wherein the positive anode voltage is kept applied to theanode lead-out electrode A1, however, the cathode lead-out electrode C2is selected in place of the cathode lead-out electrode C1. Picture cellsthus selected are indicated at oblique lines on a second line.

Thus, phosphors R, R, R, . . . on the second line on which oblique linesare drawn are permitted to emit light. Likewise, luminescence or lightemission of the phosphors R is controlled by color data on redconcurrently applied to the gate lead-out electrodes GT1 to GTl.

Such driving is repeated in turn, so that when scanning of the cathodeelectrode Cn is completed, a state shown in FIG. 21(c) is obtained. Inthe state of FIG. 21(c), the positive anode voltage Ea is applied to theanode lead-out electrode A2 and the cathode lead-out cathode C1 isselected, resulting in picture cells on the first line on which obliquelines are drawn being selected. More particularly, phosphors G, B, G. B,. . . on the first line which are deposited on the anode electrodes206-1 and 206-3 connected to the anode lead-out electrode A2 arepermitted to emit light and light emission of the phosphors iscontrolled by color data on green or blue concurrently applied to thegate lead-out electrodes GT1 to GTl. This results on all picture cellson the first line being subject to luminous control.

Then, A state shown in FIG. 21(d) is obtained, wherein the positiveanode voltage Ea is still kept applied to the anode lead-out electrodeA2, however, the cathode lead-out electrode C2 is selected in place ofthe cathode lead-out electrode C1, resulting in picture cells on thesecond line on which oblique lines are drawn being selected. Moreparticularly, the phosphors G, B, G, B, . . . on the second line arepermitted to emit light and light emission of the phosphors iscontrolled by color data on green or blue concurrently applied to thegate lead-out electrodes GT1 to GTl.

Thus, the cathode lead-out electrodes C1 to Cn are scanned in turn whilethe positive anode voltage is kept applied to the anode lead-outelectrode A2, so that scanning of the last cathode lead-out electrode Cnis completed, all picture cells of the display device are permitted toemit light while the luminescence is kept controlled, so that an imagefor one frame is displayed.

FIG. 20(a) shows an output pulse of an anode driver for driving theanode lead-out electrode A1, FIG. 20(b) shows an output pulse of theanode driver 64 for driving the anode lead-out electrode A2, FIG. 20(c)shows an output pulse of the cathode driver 60 for driving the cathodelead-out electrode C1, FIG. 20(d) shows an output pulse of the cathodedriver 60 for driving the cathode lead-out electrode C2, FIG. 20(e)shows an output pulse of the cathode driver 60 for driving the cathodelead-out electrode C3, and FIG. 20(f) shows an output pulse of thecathode driver 60 for driving the cathode lead-out electrode Cn.

FIG. 20(g) shows color data applied from the gate driver 63 to the gatelead-out electrode GT1, FIG. 20(h) shows color data applied from thegate driver 63 to the gate lead-out electrode GT2, FIG. 20(i) showscolor data applied from the gate driver 63 to the gate lead-outelectrode GT3, FIG. 20(j) shows color data applied from the gate driver63 to the gate lead-out electrode GT1, FIG. 20(k) shows an enable signalfor controlling operation of the cathode driver 60, FIG. 20(m) shows alatch pulse indicating a latch timing of each of the latch circuits 59and 62, FIG. 20(n) shows a shift clock fed to the shift register 61, andFIG. 20(p) shows color data fed from the gate driver 63 to the gatelead-out electrodes GT1 to GTn of the gate electrode 3.

Now, the manner of operation of the drive circuit constructed asdescribed above will be described with reference to FIGS. 20(a) to20(k), 20(m), 20(n) and 20(p).

Image data are fed to the memory write control circuit 53, in which awrite timing of the image data is subject to control. Also, the colordata are stored for every color in synchronism with a clock generated bythe clock generator in the video memory 54. The memories 54-1 to 54-3 ofthe video memory 54 have color data on the colors R, G and B storedtherein respectively. The color data thus stored in the memories areread therefrom depending on the addresses of the address counter 556while being subject to the color section circuit 57 and then held in thebuffer registers 55-1 to 55-3.

The buffer registers 55-1, 55-2 and 55-3 are subject at an output timingthereof to control by the color selection circuit 57, so that the colordata held therein are fed in the same order as the picture cells onwhich oblique lines are drawn in FIGS. 19(a) to 19(d) to the shiftregister circuit 61. The shift register 61 shifts the color data bymeans of the shift clock SCLK shown in FIG. 20(n).

Of the picture cells on the first line of the image display device 50,color data on red corresponding in number to the anode electrodes 206-2connected to the anode lead-out electrode A1 are fed to the shiftregister 61, which then shifts the color data. Then, the color data arelatched by the latch pulse shown in FIG. 20(m) in the latch circuit 62.Output data of the latch circuit 62 are applied to the gate driver 63.

The display control timing circuit 52 controls the anode driver 64, tothereby cause the anode driver 64 to a positive anode voltage to onlythe anode lead-lead electrode A1 as shown in FIGS. 20(a) and 20(b).Also, the display control timing circuit 52 feed the shift register 58with the latch pulse shown in FIG. 20(m) as a shift pulse, resulting ina scan signal output from the control circuit 52 being shifted. Anoutput of the shift register 58 is latched by the above-described latchpulse in the latch circuit 59, so that the latch circuit 59 outputs thescan signal shifted at every latch pulse. The scan signal shifted isthen fed to the cathode driver 60.

This results in output pulses being fed from the cathode driver 60 tothe cathode lead-out electrodes C1, C2, C3, . . . , Cn of the imagedisplay device 50 in turn as shown in FIGS. 20(c), 20(d), 20(e) and20(f), so that the cathode lead-out electrodes C1, C2, C3, . . . , Cneach are scanned at a timing of the latch pulse described above.

At this time, color data shown in FIG. 20(g), 20(h), 20(i) and 20(j) arefed from the gate driver 63 to the gate lead-out electrodes GT1 to GTlin synchronism with scanning of the cathode lead-out electrodes C1 toCn, so that color data on the colors R, R, . . . , R shown in FIG. 21(a)are fed to the gate lead-out electrodes GT1 to GTl while the cathodelead-out electrode C1 is kept driven as shown in FIG. 20(c).

Thus, the phosphors R on the first line of the image display device 50is subject to luminous control as shown in FIG. 21(a). Then, the cathodelead-out electrode C2 is selected at a timing of the next latch pulse.At this time, the next color data on red have been shifted into theshift register 61 by means of the shift clock SCLK, so that the imagedisplay device 50 controls luminescence or light emission of the picturecells R on the second line as shown in FIG. 21(b).

Such scanning as described above is successively carried out, so thatscanning of the last cathode lead-out electrode Cn leads to control ofluminescence of the picture cells R for one frame. Then, the displaytiming control circuit 52 controls the anode driver 64, resulting in theanode driver 64 applying a positive anode voltage Ea to the anodelead-out electrode A2.

Concurrently, color data shown in FIG. 20(g), 20(h), 20(i) and 20(j) arefed from the gate driver 63 to the gate lead-out electrodes GT1 to GTlin synchronism with scanning of the cathode lead-out electrodes, so thatcolor data on the colors G, B, G, . . . B shown in FIG. 21(c) on whichoblique lines are drawn are fed to the gate lead-out electrodes GT1 toGTl while the cathode lead-out electrode C1 is kept driven as shown inFIG. 20(c).

Thus, the picture cells G and R on the first line of the image displaydevice 50 on which oblique lines are drawn are subject to luminouscontrol as shown in FIG. 21(c). Then, the cathode lead-out electrode C2is selected at a timing of the next latch pulse. At this time, colordata on green and blue have been shifted in the shift register 61 bymeans of the shift clock SCLK, so that the image display device 50controls luminescence or light emission of picture cells G and B on thesecond line shown in FIG. 21(d) on which oblique lines are drawn.

Such scanning as described above is successively carried out, so thatscanning of the last cathode lead-out electrode Cn leads to control ofluminescence of the picture cells G and B for one frame. Thus, a colorimage for one frame is displayed on the image display device 50.

The drive circuit for the image display device reduces the number oftimes of changing-over of the anode electrodes to which a high voltageis applied, to thereby lighten a burden on the drive circuit for theanode lead-out electrodes, resulting in the drive circuit being simplyconstructed. Also, the anode lead-out electrode unselected is biased toa negative voltage, mixing of colors being prevented.

The embodiments described above each have the phosphors of red, blue andgreen luminous colors incorporated therein. Alternatively, the presentinvention may be constructed in such a manner that one kind of aphosphor having an increased luminous wavelength range and filtersdifferent in transmission wavelength characteristics are arranged, tothereby obtain a plurality of luminous colors such as red, blue, greenand the like through the phosphor. In this case, luminouscharacteristics of the phosphor itself are different from those of eachof luminous colors obtained through the filters, so that a phosphor of aluminous color having the lowest luminance may be conveniently used asthe single phosphor.

As can be seen from the foregoing, the image display device of thepresent invention has only two anode lead-out electrodes incorporatedtherein, to thereby permit each of the anode lead-out electrodes to beled out of each of both sides of the device, resulting in eliminatingmulti-level crossing. Also, such construction of the present inventionleads to dividing of the anode electrodes into two groups, to therebypermit the duty to be increased to a level 3/2 times as large as that inthe prior art in which anode electrodes are divided into three groups,resulting in providing an image of increased brightness.

Also, in the present invention, the anode electrodes divided into twogroups are selectively scanned, to thereby permit the picture cells toselectively emit light, resulting in providing a color image free ofcolor bleeding.

Further, the control electrodes arranged between the gate electrodeseffectively prevents spreading of electrons, so that the number of anodeelectrodes may be substantially increased to provide an image with highdefinition. Thus, the device of the present invention, when it isapplied to a microwave vacuum tube, a light source, an amplificationelement, a high-speed switching element, a sensor or the like, providesan anode or collector with a sufficient amount of electrons, to therebysignificantly increase sensitivity and stability of an image obtained.

In addition, the present invention effectively prevents color mixing andleakage luminescence irrespective of a distance between the phosphorlayer and the gate electrode, to thereby permit an anode voltage to beincreased to a level sufficient to increase luminance.

Furthermore, the present invention prevents color mixing withoutrequiring selection by means of the anode electrodes, to therebyeliminate switching at a high voltage.

Also, the present invention permits positive ions due to gas such asresidual gas to be absorbed by the diffusion prevention electrodes byapplying a negative potential to the electrodes, to thereby preventdeterioration of the emitter electrodes due to adhesion of the ionsthereto.

Furthermore, The present invention is so constructed that the diffusionprevention electrodes are arranged on the same plane as the gateelectrodes. Such construction permits the structure of the presentinvention to be highly simplified as compared with the prior art inwhich diffusion prevention electrodes are arranged between cathodes andanodes, leading to a multi-layer structure. Thus, the present inventionaccomplishes a decrease in manufacturing cost.

Also, the present invention may be so constructed that the anodeelectrode provided thereon with the phosphor which is expected to bedecreased in luminance is fed with electrons from two FECs. Suchconstruction permits the phosphor to be increased in luminance.

While preferred embodiments of the invention have been described with acertain degree of particularity with reference to the drawings, obviousmodifications and variations are possible in light of the aboveteachings. It is therefore to be understood that within the scope of theappended claims, the invention may be practiced otherwise than asspecifically described.

What is claimed is:
 1. An image display device comprising:an airtightenvelope including an anode substrate and a cathode substrate arrangedso as to be opposite to each other; cathodes electron emitting elementsof the field emission type which include cathode conductors arranged onan inner surface of said cathode substrate, emitter electrodes providedon each of said cathode conductors and gate electrodes arranged on eachof said cathode conductors through an insulating layer; a displaysection formed on an inner surface of said anode substrate; said gateelectrodes each having a selection voltage applied thereto to causeelectrons emitted from said emitter electrodes to impinge on saiddisplay section, resulting in said display section carrying out aluminous display; diffusion prevention electrodes arranged on the sameplane as said gate electrodes in a manner to interpose each of said gateelectrodes between each adjacent two of said diffusion preventionelectrodes and applied thereto a voltage lower than said selectionvoltage when said selection voltage is applied to at least said gateelectrodes positioned in proximity to said diffusion preventionelectrodes, to thereby prevent diffusion of electrons emitted from saidemitter electrodes.
 2. An image display device as defined in claim 1,wherein said diffusion prevention electrodes each have a voltage of 0 Vor less constantly applied thereto.